Time switch



Aug. 20, 19406 D. s. CAMERON TIME SWITCH Filed Dec. 30, 1937 019) THEE/705747 m L M w b Mn om r ta Q im W6 A m .6

Patented Aug. 20, 1 940 UNITED STATES TIME SWITCH Donald G. Cameron, Lynn, Mass, asslgnor to General Electric Company, a corporation of New York Application December 30, 1937, Serial No. 182,539

Claims.

My invention relates to time switches and although not limited thereto is particularly designed for use in systems of automatic control for domestic heating apparatus.

In the form shown the time switch employs two sets of time controlled contacts. One set is employed to open and closea circuit at predetermined adjustable times in a given period of time such as a 24 hour period and may thus be used to shift control from day to night thermostat and vice versa. This switch is of simple construction and operation. The lines of the circuit controlled may be connected directly to the switch contact blades and manual means is provided to move these blades to permanently open or to permanently closed position to suspend automatic control. The other set of time controlled contacts is arranged to close a circuit for a short interval of time periodically. The number of times that this switch is closed during a 24 hour period may be adjusted and also the duration of closure may be adjusted in a novel manner. This set of contacts may thus be used to momentarily start up the furnace at intervals and prevent a coal fire from going out, entirely in case furnace operation is not otherwise called for.

The features of my invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. For a better understanding of my invention reference is made in thefollowing description to the accompanying drawing in which Fig. 1 represents a perspective, somewhat exploded view of my improved switch and one possible way of connecting it with a furnace control system. Figs. 2 and 3 represent different positions of thecam-operated switch shown at right in Fig. 1.

Referring to Fig. 1, the time switch is driven by a synchronous motor indicated at ID. The motor is connected through a speed-reducing gear train II and a friction clutch I2 to a shaft |3 so as to drive said shaft at one revolution per hour in a clockwise direction. A minute hand H of a clock is mounted on the front end of this shaft. Concentric with shaft I3 is a, hollow hour hand shaft IS on which is mounted the hour hand l6, and this shaft I5 is driven from shaft |'3 in a clockwise direction one revolution in twelve hours through the usual back gears l1, l8, l9 and 2|]. Shafts l3 and I5 have been broken away over the main time switch mechanism to more clearly expose the latter. The clock hands .will cooperate with the usual clock dial (not shown) to indicate time.

The main time switch has its operating mechanism supported by a clock plate 2| which has been mostly broken away in the drawing. Extending through this plate are bearings 22 and 23 for rotatively supporting cam shafts 24 and 25. These cam shafts are driven from the hour hand 5 shaft IS in a clockwise direction, one revolution in 24 hours, through gears 26, 21, 28 and 29. Gears 28 and 29 are secured to shafts 24 and 25 respectively. Also secured to shafts 24 and 25 are cam discs 30 and 3|, having-spiral side cam surfaces. The cam 30 cooperates with a camfollower 34, projecting to the rear from a dial disc 35. Dial disc 35 is rotatively mounted on the bearing housing 22 but is normally held against rotation by a friction spring 36' which is compressed between disc 35 and plate 2|.

Cam 3| cooperates in a similar manner with a cam-follower 31 projecting to the rear of an adjustable dial plate 38. Shafts 24 and 25 may slide endwise in their bearings as well as rotate therein.

Cam shaft 24 together with cam plate 30 is at all times urged axially towards the front with the cam plate against cam-follower finger 34 by a spring 39, which spring is also a resilient switch contact. This spring switch member has its lower end rigidly supported. Also, its lower end constitutes the terminal to which the external circuit wire may be connected. A reduced rear end portion of shaft 24 rests against the spring contact member 39 near its upper end adjacent contact 40 so that, as shaft 24 is moved endwise to the rear or to the front by cam 30, contact 40 is likewise moved back and forth.

shaft 25 likewise has reduced rear extension against which a spring switch contact member 4| presses. Member 4| has its upper end extending in overlapping relation and in front of contact and is provided with a cooperating contact 42 on its rear face. The lower; end of contact mem- 40 ber 4| is likewise rigidly supported. in a support insulating member 4| from 39 and constitutes the other line terminal 33 of the switch. The slope of the cam surfaces are such as to produce a slow, substantially uniform rearward movement 45 of shafts 24 and 25, as these shafts are rotated once in a given 24 hour time period except when the cam followers 34 and 31 ride over the step in the cams, at which time there is a quick forward movement of the shafts. The gear 21 is purposely made wide enough to mesh with gears 28 and 29 at all times, regardless of the endwise position of the'shafts 24 and 25.

The quick forward movement of shaft 24 is made use of to close switch contact 4|! onto con- M spect to a fixed index or pointer 43 to indicate g to hold shaft 44 and cross bar 45 in any one the time when cam-follower 34 will drop over the step in cam 30 to close the switch. in the example given the switch is intended to close in the evening between, say 8 p. m. and midnight. and the graduations-on dial '35 will thus, read from 8-12 and the indication opposite pointer 43 will designate the time as given by the clock hands when the switch will close. The openin an; closing adjustments are independent of each ot er.

The switch is intended to open in the morning, say between 4 a. m. and 8 a. m. and dial 38 will have the approximate part of its periphery graduated accordingly and otherwise arranged to be set so that the switch will open at a time designated on such dial. The shape of the cam surfaces and the spacing of contacts 40 and 42 are such that within the time setting range indicated, the switch will remain closed at night and will remain open during the day. That is, the device may be set to close the switch as early as 8 p. mzin the evening and have it remain closed until as late as 8 a. m. in the morning and remain open until 8p. m. again, or, it may be set to be closed between 12 midnight and 4 a. m. and remain open the remainder of the 24 hour period, etc. When. open, the contacts remain at about the same spacing although both contacts are gradually moved to the rear during the open and closed periods. The setting range may be extended somewhat beyond the limits indicated above but generally, for the purpose for which the switch is intended, the range given will suilice.

Associated with the switch is a manually rotatable shaft 44 having an insulated cross bar 45 at its rear end. This device is to lock the switch in either the closed or open position or to permit automatic operation as desired.

The insulated cross bar 45 cooperates with fingers 46 and 41 which are integral with and extend downward from joints on the upper portions of switch members 39 and 4| which are nearer the contactsthan the joints where the automatic control operates on these contact members. These fingers are bent away from the cross bar adjacent thereto so as to form cam surfaces and to permit of a cam action when the shaft 44 and cross bar 45 are turned by hand. In the horizontal intermediate or neutral position of the cross bar shown, it does not interfere with the automatic opening and closing of the switch at contacts 40 and 42. If the cross bar be turned to the left so that its right end is raised and its left end lowered through an angle of about 45 degrees, finger 41 will be forced to the rear, forcing contact bar 4| to the rearaway from the end of shaft 25 to close the switch in all positions of cam 30. On the other hand, if bar 45 be turned about 45 degrees clockwise from the position shown, finger 46 contacts bar 45 and contact 40 will be forced to the rear away from contact 42 and the switch will remain open in all positions of cam 3|. A flat, resilient finger 48 is secured to and turns with cross bar 45 and shaft 44. The free end of this finger bears against one of the three squared surfaces at 49 cut in the plate 2| and serves as a resilient lock steps and member 52 six steps.

of the three positions mentioned until turned to some other position by hand.

It is thus seen that I have devised a simple switch having few parts but one which accom-' is energized, it sets into operation a stoker motor and a draft fan to increase the heatgiven out by a furnace. The relay is under the control of day and night thermostats 5| and 52. It may be assumed that thermostat 5| is set so as to close its contact at 53 when the temperature drops below 70 degrees F. and to open its contact when the temperature rises to '71 degrees F. It may further be assumed that the night thermostat 52 is set so as to close its contacts at 54 when the temperature drops below 64 degrees F., and to open its contacts when the temperature rises to 65 degrees F. The timeswitch already described controls a transfer relay 55 which serves to transfer the control of the furnace relay from the day thermostat 5| to the night thermostat 52 at some time in the evening, depending on the'setting ofdial 35, and back again to the I day thermostat 5| at some time in the morning,

depending on the setting of dial 58. To this end,

relay is energized from a source 56, when switch contacts 40--42 are closed. This con nects furnace control relay 50 with the night thermostat 52 through theupper contacts of relay 55 and source 55. Thus, during the night time, whenever thermostat 52 calls for heat, relay 50 will be energized. During the day time, when switch contacts 40-42 are open, relay 55 is deenergized and the furnace control relay 5!! is under control of the day thermostat 5| through the lower set of contacts of relay 55.

Now, it sometimes happens when the temperature is mild, particularly when the furnace is operating on the night thermostat, that no heat is called for by the thermostat for long periods of time. This may cause a coal furnace fire to go out or to so nearly go out as to fail to respond with any degree of desirability to a subsequent .closing of the thermostat. To prevent this, the

' ever several hours, the duration of closure of the contacts and the interval between closure times both being adjustable to correspond with the several different kinds of conditions likely to be met with in practice.

This switch mechanism includes a cam shaft 55 driven from gear I! and some intermediate gears so as to operate at a rate of one revolution in three hours, for example. The cam shaft has on it several cam members, three in this instance,

designated 50, GI and 52.

These cam members operate counter-clockwise. Member 50 has two steps, member 5| three The steps of individual cams in each cam member are equally spaced. The contact supporting block 63 may be slid along its supporting post 64 parallel with cam shaft 59 so as to cause the contact mechanism to be operated by any one of the three cam members that may be selected. The individual cams on all of the cam members are the same, that is the maximum and minimum radii of the steps are equal in all cases. Hence, if the contact mechanism is opposite cam member 62, it will be operated every half hour, if opposite cam member 6 I, it will be operated every hour, and if opposite cam member Ell, it will be operated every hour and a half, but the individual operations will be will be similar in all cases. It is seen then that by moving the contact block 63 and the parts carried thereby along post 64, the time interval between contact operations may be varied over a suitable range.

The contact mechanism is held in proper position by post 64 and by the fingers 64 and 65 extending from the upper part of the block and embracing a post 66. Finger B5 is resilient and allows slight rotation of the block 63 on post 64 during operation of the contact mechanism. It also permits the block to be rotated clockwise from the position shown in order that it may be moved endwise. Theupper metal part 6? of which finger 65 is a partyis provided with three notches 68 in its forward edge. These notches are spaced apart the distance of the cam members on cam shaft 59 and serve to lock the contact block in its three operative positions with respect to the three cam members. This locking is done by causing the appropriate notch to slip over a projection 69 in the plate it. As represented in the drawing the block at and its contact mechanism is positioned in operative relation with cam 62 and hence the contact device will be operated every half hour. To adjust for operation every hour the contact block and the parts carried thereby are rotated slightly about post 64 in a clockwise direction until the notch in plate Bl which is engaged with the locking projection 69 is free of said projection. Then the contact block is slid along post 56 towards the front until the middle notch in plate 6? is in line with plate it and its locking extension 69. Then the contact block is allowed to rotate counter-clockwise on post 6 3 under the light tension of spring t l until the block is locked from further endwise movement by engagement of projection 69 in the middle notch of plate 8?.

The contact finger is then aligned with camits upper free end opposite a cooperating con-' tact button on the lower side of contact finger 58. Contact finger 58 is also of metal, is relatively flexible and is long enough to engage with and at times to be moved by the operating cam. Contact fingers 51 and 58 have their right hand ends secured in the insulating block 63 and insulated from each other therein. The wires leading to the external circuit controlled by this contact device are connected to contact fingers 51 and 58 as indicated in Fig. 1. Above contact finger 58 is another finger II extending from block 63 out over the operating cam. Finger H is preferably of insulating material and is relatively stifi and its free end extends beyond the free end of contact finger 58 by an adjustable amount. In: the structure shown cam follower H is an extension of a fiber-strip 12 seen projecting to the rear ofblock 63 from beneath plate 61. Strip I2 is slotted to accommodate a screw 13. When the screwis loosened the strip 12 may be adjusted to cause its end finger H to extend a greater or less amount beyond the end of contact finger 5']. It is this adjustment which determines the relative length of time on and time off of the contact device. The resilient finger 64 which engages with the under side of post 66 is suitably secured to the block 53 between plate 61 and insulating strip 12. The block 63 is free to turn on post 64 and in the operation of the contact device by the cam memher there is a slight back and forth rotational movement of block 53 on post 54 as a pivot, such rocking movement however is insufficient to raise plate 6'1! so as to disengage a notch 63 therein from projection $9. The extent of this rotational movement corresponds substantially to the amount by which insulating finger H is raised and lowered by engagement with the high and low parts of the cam. Thus, Fig. 2 shows the finger it in approximately its highest position and Fig. 3 shows this finger in approximately hence both move up and down together with the rocking movement of block 63. The intermediate contact finger 58 is relatively flexible and is normally biased, as shown in Figs. 1 and 2., to close its contact on the contact of finger 57. However, when the finger ll drops off of the step in the cam and contact finger 5i is lowered, the flexible contact finger 55B is prevented from following finger 5i downward by reason of its striking the cam surface as shown in Fig. 3, and hence the contacts open. Thusit is seen that when the insulating contact finger H rests directly on the cam the contacts are closed (Figs. 1 and 2) and when contact finger 58 rests on the cam the contacts are open (Fig. 3).

It is further evident that when finger 58 drops ofi the step in the cam the contacts close with aquick action and when insulating finger ill drops off the step in the cam, the contacts open with a quick action. The contacts thus open and close quickly and without hesitation which is desirable.

Now it will be seen that the time during which the contacts are closed during an operating cycle is the period between the dropping of fingers 58 and il over the same step in the cam. Also the time during which the contacts are open is the period between the dropping of finger H over one step in the cam and the dropping of finger 53 over the next approaching step in the cam. If we make fingers ii and 58 exactly the same length so that they drop over the same step togetherthe contacts will remain open continuously. Hence, We can reduce the on period by any desired amount down to zero by decreasing the difference between the effective lengths of effective length of insulating finger ll adjustable.

In Figs. 2 and 3, for example, we may reduce the length of the "on period and increase the length of the off period by reducing the effective length of flnger M.

It is thus seen that by means of the cam and contact mechanism described we may materially vary the length of the operating cycle by selection of the desired cam 59, hi or 62 and we may vary the relative duration of on and ofi periods during an operating cycle by adjusting the effective length of finger ii.

Let us assume that this mechanism is adand that the on period is adjusted for a duration of one minute. This assures that regardless of the operation of the day and night thermostats 5i and 52, the furnace control relay 5i will be energized at least one minute every hour, and this will avoid the inconvenience of having the furnace go out entirely in case no heat is called for by the thermostats, but without producing any appreciable amount of heating. It may often happen that the circuit of relay 50 will be closed at contacts 51 and 58 at a time when the relay 50 is already energized by one of the thermostats. This will do no harm since the connection made by contacts 61 and 5B is merely a parallel connection to the one closed by the connected thermostat.

The manual control Ml of switch contacts 60 and 42 is desirable in the application described. For example, when the. family retires later than usual in the evening, turning switch 44 to 0113" position assures that the temperature will be maintained by the day thermostat until switch is again turned to neutral position. When the'family is to be away fromhome'during the day time, switch 66 may be. turned to on position, which will then assure the maintenance of a temperature according to the setting of the night thermostat until such time as switch M is again turned to neutral position. Such use of switch 44 does not disturb the setting of dials 35 and 38 or of the thermostats or the function of the contacts 51 and 58.

Itis thus seen that I have provided a relatively simple, yet convenient and reliable time switch for taking care of all of the time functions met with in furnace control. particularly suited for furnace control ,applica: tions, I do not wish to limit my invention to this particular use.

All of the adjustments heretofore described are made independently of each other. For example, adjustment of cam finger 36 in no way alters the result of adjusting the number of cycles, of operation of contacts 51 and 5B in a given 24 hour time period or the relation between the on and off period of contacts 51 and 58 during their cycle 'of operation. By making the ratio between the 24 hour time period andthe time cycles of operation of contacts 51 and 5 8 during such period an integer, the sequence of operation of all contacts will remain the same in subsequent 24-hour periods for any given adjustment. This is not important in the application described but will be important in some process applica- .tions where a given program or sequence of operation is to be repeated on a device such as reof synchronized contact mechanisms.

In accordance with the provisions of the patent I justed for an operating cycle of once per hour.

Although the switch is lay switch 50 under the joint control of both sets statutes, I have described the principle of operation of my invention together with the apparatus which I now consider tovrepresent the best embodiment thereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a time switch a pair of parallel shafts mounted for rotational and axial movements, a pair of metallic resilient contact members, an insulating supporting means securing one end of each member in spaced relation, the other ends of said members being flexed to bear against the ends of said shafts, to urge said shafts in the same 'txialdirection, extensions from the flexed ends of said contact members which overlap and form cooperating contacts a timer motor for rotating said shafts at the same speed, cam means on each shaft, and 'cam followers adjustable about each shaft for moving said shafts slowly endwise against the bias of said springs and suddenly releasing said shafts for limited reverse movement at different times as they are rotated by said timer motor, said cooperating contacts being spaced to close when one shaft is moved endwise upon being released and to open when the other shaft is moved endwise on being released. v

2. In a time switch a pair of parallel shafts mounted for rotational and axial movements, a

timer motor for rotating both shafts at the same speed, cam means associated with each shaft for causing slow axial movements of said shafts in one direction as the shafts are rotated through causing the quick return axial movements of said shafts when that is permitted, said contact members having overlapping portions with cooperating contacts thereon, said cam means beingadjustable to cause the quick return movements of said shafts to occur at different times, said contacts being so spaced as to close in response to 'the quick return movement of one shaft and to open in response-to the quickreturn movement of the other shaft.

3. In a time switch a pair of metallic resilient contact members fixed atone end in insulating supports, said members having overlapping co-' operating contact portions which may be flexed towards and away from each other to establish and interrupt an electric contact between them,

time controlled means for flexing said members to establish and interrupt said electrical contact at predetermined adjustable times, and a manual operating device for selectively flexing said members, said manual operating device having three positions, one position for flexing one of said.

members in a direction and to an extent to establish said contact irrespective of the operation of said time controlled means, another position for flexing the other of said members in a direction and to an extent to interrupt said contact irrespective of the operation of said time controlled means and a third position in which neither of said members are flexed thereby but in which said members are free to be flexed by said time controlled means.

4. In a time switch a pair oi metallic resilient members fixed at one end to an insulating support and extending away therefrom in parallel relation, said members having extensions at their other ends which project towards each other in overlapping relation, cooperating contacts on said overlapping extensions, time controlled means for automatically moving said extensions towards and away from each other to open and close said contacts at predetermined adjustable times, and

manual means for suspending the automatic opening and closing of said contacts by said time controlled means and doing it manually, comprising a manually rotatable shaft extending between said resilient members, an insulating bar on said shaft, cam shaped projections extending from the movable parts of said resilient members adjacent said bar, said shaft and bar having three rotative positions, a central neutral position where automatic operation is not suspended, another position where one contact member is forced away from the other to open said contacts and another position where the other contact member is forced towards the first to close said contacts, and means for locking said shaft in any one of its three positions.

5. In a time switch a support, a pair of resilient contact members secured at one end to said support, said members having overlapping extensions at their other ends carrying cooperating contacts, time controlled means for flexing said members to automatically open and close said contacts at predetermined adjustable times, and

manual means for flexing said members to open cooperating contacts 

